This application is for the continuation of an observational study evaluating screening for NB in infants. The Quebec NB Screening Project was initiated in 1989 to assess the clinical and biologic aspects of screening infants for NB in North America. The effects of mass screening on NB outcome have been determined after measuring catecholamine metabolites in urine specimens collected at three weeks and six months of age from over 430,000 infants born in Quebec during 1989-1994, over 90% of the corresponding birth cohort. Subjects have been followed a minimum of 18 months. Follow-up includes NB incidence and mortality in the whole birth cohort, and the results compared to NB outcomes from several concurrent population-based non-screened control groups in North America. Although the critical endpoint of mortality reduction has not yet been determined, there has been a marked increase in the incidence of NB in the Quebec cohort from patients diagnosed both preclinically and clinically, indicating a marked halo effect from the screening program. There has been no decrease in the incidence of unfavorable advanced stage disease. The applicant now propose to conclude the screening project in the year 2000 by: 1) determining the mortality from NB for all children born in the original birth cohort, with comparison to the population-based non-screened control groups; and 2) determining if the increased incidence of NB in the screened cohort decreases in the post-screened cohort commencing with infants born after screening.